You can edit almost any aspect of your podcast from the "Edit" tab that appears on your dashboard. Just log in to your account and then click the "Edit" button.
A menu will be displayed with the options to edit your podcast, go to "Categories" section:
You can choose the one that best suits your podcast and select the primary and secondary categories.
At the end of any change, always remember to click on the "Save" button.
Important: RSS updates your feed in real-time, however, each platform has a different update time with your feed. For this reason, your data may take time to be updated on the platform where your show is published.